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Effect of flow on the acoustic resonances of an open-ended ductThe effect of flow on the acoustic resonances of an open-ended, hard-walled duct is analyzed. The flow produces acoustic losses both in the interior of the duct and at the ends. Unless the duct is very long, typically 100 times the diameter, the losses at the ends dominate. At flow Mach numbers in excess of 0.4 the losses are so large that axial duct resonances are almost completely suppressed. The plane-wave Green's function for the duct with flow is expressed in terms of the (experimentally determined) pressure reflection coefficients at the ends of the duct, and the flow dependence of the complex eigenfrequencies of the duct is obtained. Some observations concerning the noise produced by the flow in the duct are also reported.
Document ID
19760027447
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ingard, U.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Singhal, V. K.
(MIT Cambridge, Mass., United States)
Date Acquired
August 8, 2013
Publication Date
October 1, 1975
Publication Information
Publication: Acoustical Society of America
Subject Category
Acoustics
Accession Number
76A10413
Funding Number(s)
CONTRACT_GRANT: N00014-67-A-0204-0019
CONTRACT_GRANT: NGR-22-009-805
Distribution Limits
Public
Copyright
Other

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